Flexible display is referred to as bendable display or soft display. It is made of a soft material, and its main structure includes a flexible substrate, an intermediate display medium and a package.
The flexible substrate is an important component part of the whole flexible display, and its performance has an important influence on both the quality and lifetime of the flexible display. At present, materials that may be used for a flexible substrate include ultrathin glass, a metal foil or a polymer film. The polymer film may be polyethyleneterephthalate, polyethylenenaphthalate, polycarbonate, cyclic polyolefin, polyethersulfone and polyimide, etc. Due to its excellent high temperature resistance, good mechanical property and excellent chemical stability, polyimide substrate attracts much attention.
For a polyimide substrate, a piece of glass is taken as the base substrate, and a polyimide solution, or a solution of its precursor, polyamic acid, is coated on the glass base substrate; then, a polyimide film is obtained after curing; next, a display medium, a water and oxygen shielding layer and a package layer are assembled on the surface of the polyimide film; and finally, the glass base substrate is removed from the device prepared via a Laser Lift Off (LLO) process, thereby a display that takes a polyimide film as a flexible substrate is obtained.
However, because polyimide substrate does not have the function of laser screening, during the process of sealing and curing or removing the glass base substrate via a Laser Lift Off process, laser tends to directly influence the liquid crystals inside the display panel, thus the display quality may be influenced.